1. Field of the Invention
The present invention relates to a control arm for a motor vehicle suspension system and, more particularly, to a lighter weight lower control arm for a motor vehicle suspension system that meets required performance attributes for the suspension system.
2. Description of Prior Art
Lower control arms are used in motor vehicle suspension systems. Currently, lower control arms used m the automotive industry are usually made as an assembly of steel stampings, which are welded together. Some lower control arms used for heavy duty applications (i.e., Sport Utility Vehicles (“SUV's”) or high performance vehicles (i.e., sports cars)) are provided as one-piece cast gray or ductile iron lower control arms. Either of these approaches results in a suspension system having considerable weight. The weight of these lower control arms negatively affects the ride and handling characteristics of these vehicles, as well as increasing fuel consumption.
In recent years, some luxury and sport utility vehicle (SUV) manufacturers have begun using one-piece cast aluminum lower control arms to obtain the required vehicle handling performance. Generally, this approach substitutes aluminum for ferrous metals. However, the cost of these one-piece aluminum components is generally considered to be too great for wider use in the automotive industry. Some manufacturers have tried to reduce the weight of lower control arms by making the aluminum castings as hollow cast components. This reduces the weight of the castings but increases their manufacturing costs substantially.
Numerous approaches are known in the automotive industry for making control and suspension arms. For example, U.S. Pat. No. 6,311,996 to Kato et al. discloses a suspension arm comprised of a bent arm member that is made of aluminum alloy and is manufactured by extrusion. U.S. Pat. No. 6,241,267 to Dziadosz et al. discloses a control arm for use in a motor vehicle suspension system that is comprised of two W-shaped cross section members, which are coupled together with bushings that include a compressible member. U.S. Pat. No. 6,149,198 to Klaas discloses a rear axle cradle that is constructed from two hydroformed aluminum tubes, which are connected together. U.S. Pat. No. 5,695,213 to Nakamura et al discloses a suspension arm that is formed by two overlapping shells, which form a tube. The shells are welded together U.S. Pat. No. 5,662,349 to Hasshi et al. discloses a suspension arm having an L-shaped arm body in the form of a hydroformed pipe. U.S. Pat. No. 5,338,056 to Vrana et al. discloses an upper control arm for a motor vehicle suspension system having a triangular shaped hollow cross section. Further, U.S. Pat. No. 4,625,995 to Aubry et al. discloses a suspension arm made of resin fiber.
While numerous approaches for making control and suspension arms are known in the art, there is considerable room for improvement in the field to reduce the weight and cost of control and suspension arms, particularly lower control arms for motor vehicle suspension systems, while not sacrificing performance characteristics.